1. Field of the Invention
The invention relates to a heat-dissipating device, more particularly to a heat-dissipating device with a grounding capability.
2. Description of the Related Art
With the increase in the computing speeds of central processing units (CPU) and other computing semiconductor chips, the heat generated thereby is also on the rise. In order to prevent undesired heat accumulation, which can result in chip malfunction or damage, heat-dissipating devices are widely used to achieve a heat-dissipating effect. Since the heat-dissipating devices usually include a heat-conductive and electrically conductive metal member that abuts against a heat-radiating side of semiconductor chips, when the metal member is grounded, an electromagnetic interference (EMI) shielding effect can be achieved at the same time.
Referring to FIG. 1, a conventional heat-dissipating device 1 is shown to be adapted to be mounted on a circuit board 2. The circuit board 2 includes a main body 21 with an intermediate grounding layer 22, and a socket connector 23 mounted on a top surface of the main body 21 for mounting an electronic component 3, such as an integrated circuit chip, on the main body 21. The heat-dissipating device 1 includes a heat-dissipating member 11 formed with a plurality of heat-dissipating fins 111, and a plurality of resilient members 12 connected to the main body 21 and surrounding the socket connector 23. As shown in FIG. 2, the resilient members 12 are made of a bent metal material, such as copper, and are generally C-shaped. The resilient members 12 are connected electrically, such as by soldering, to grounding points 24 of the circuit board 2 using known surface mounting techniques (SMT). The grounding points 24 are connected electrically to the grounding layer 22 (see FIG. 1). Referring again to FIG. 1, the heat-dissipating member 11 is further formed with a plurality of contact portions 112 corresponding to the resilient members 12, respectively. When the heat-dissipating member 11 is secured to the socket connector 23 by means of screw fasteners 13, the contact portions 112 abut against the resilient members 12, respectively, thereby connecting electrically the heat-dissipating member 11 to the grounding layer 22 to achieve-a grounding effect.
However, the resilient members 12 are highly susceptible to elastic deformation after a period of use due to the C-shaped configuration thereof. Moreover, inappropriate positioning or excessive exerted forces when mounting the heat-dissipating member 11 will tend to deform the contact portions 112. In both situations, poor electrical contact between the resilient members 12 and the heat-dissipating member 11 arises, thereby resulting in inferior electromagnetic interference shielding. Furthermore, since grounding of the heat-dissipating member 11 is achieved through the resilient members 12, vibrations generated during delivery or use may result in detaching of the resilient members 12 either temporarily or permanently from the circuit board 2, which can disable the electromagnetic interference shielding effect.
In addition, aside from providing a grounding effect, the resilient members 12 also provide supporting and buffering functions for the contact portions 112. As such, the resilient members 12 must be distributed around the socket connector 23. In practice, not only will there be a need to allocate a lot of space for the resilient members 12, the circuit layout on the circuit board 2 must also take into consideration both the positions of the resilient members 12 and the configuration of the heat-dissipating member 11. Increased complexity in design and difficulty in space allocation are thus encountered.
Therefore, the object of the present invention is to provide a heat-dissipating device with a grounding capability and capable of effectively shielding electromagnetic interference.
Accordingly, the heat-dissipating device of this invention is adapted for use with a multi-layer circuit board having a grounding layer and that has an electronic component mounted thereon. The heat-dissipating device comprises:
a heat-dissipating member made of a heat-conductive and electrically conductive material and adapted to be disposed on a heat-radiating side of the electronic component;
a grounding member made of an electrically conductive material, the grounding member including a grounding tail and a grounding body connected to the grounding tail, the grounding tail being adapted to pass through the circuit board to connect electrically with the grounding layer and to dispose the grounding body between the heat-dissipating member and the circuit board; and
a connecting member made of an electrically conductive material, interconnecting the heat-dissipating member and the grounding member, and adapted to be secured on the circuit board, thereby retaining the heat-dissipating member on the circuit board, the connecting member cooperating with the grounding member to make electrical connection between the heat-dissipating member and the grounding layer of the circuit board.